Replacement engine suppliers

After conducting a search of the threads, I decided to try a posting. I am looking for recommendations for sources of replacement engines. I have had a few people ask me who I'd recommend, but I have never had to replace one (knock on wood). Web searches have turned up a few, but I thought this would be a timesaver, since some of you have been down this road before. My local dealers are possible sources, but I'm looking for online or catalog sources.

Tried to order from Northern tool, 2 weeks later I found out by tracking the order that it had been canceled due to out of stock-discontinued. No notifacation-I wouldnt want to have to rely on them for anything.

I strongly recommend J-Thomas. I had to replace my engine on my Toro last month. Placed my order on a Thurs. afternoon and I kid you not, the engine arrived the next day. (shipped from Ohio to NC) I didn't even request rush delivery. I paid $545 (included shipping) for a 15HP Kohler Command.